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PowerFake Knob Controller 

Make] Projects 

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build, hack, tweak, share, discover,- 

PowerFake Knob Controller 

Written By: Daniel Walker 



Drill (1) 

Screwdriver (1) 

Soldering iron (1) 

Solder wick (1) 

or desoldering pump 

© Make Projects 

• PS/2 moused) 
You need a rotary encoder for the scroll 
wheel, not an IR transmitter/detector. A 
ball mouse is more likely to use a rotary 
encoder than an optical one. 

• R/C car wheel and tire (1) 
or other circular object you can use for 
rotating that fits in your hand easily 

• Project enclosure (1) 

• Metal rod(1) 
It needs to be of suitable length to go 
through your R/C car wheel, project box 
side, and the rotary encoder. It could be 
a thin nail or a piece from a large paper 

• Tape (1) 
/ used double-sided foam tape to mount 
the encoder. Or use glue. 

• Super glue (1) 

• Paper (Scrap) 
or Blu-Tack poster putty Page 1 of 8 

PowerFake Knob Controller 

Stripboard (Small piece) 
aka perf board (optional) 


The Griffin PowerMate is an assignable USB knob controller that you can set up for many 
purposes, such as browsing Google Earth, scrolling web pages, controlling volume, and so 
on. I took a look at some YouTube videos of it in use and thought it was literally a scroll 
mouse on its side with a fancy knob and some software. A few Googles later, and I found a 
post on the forums about a guy who made his own from a VCR spindle and an 
old mouse. I fancied a bit of that, so away I went, and this is what I came up with. 

I call it the PowerFake. It's made from an old PS/2 mouse, a project box, and an old R/C car 
wheel. The basic idea is to liberate the mouse's scroll wheel encoder from its circuit board, 
reconnect it using wires, and set it up to run off of the knob of your choice. 

© Make Projects Page 2 of 8 

PowerFake Knob Controller 

Step 1 — Gut the mouse. 

• Time to rip apart your beloved mouse. Usually these just come apart with one screw, but 
maybe your manufacturer has decided to be a bit sneaky and put screws under stickers as 
a way of telling if the warranty has been voided. 

• Here's where you'll find out if you have a rotary encoder or an I R transmitter as a scroller. 
A rotary encoder holds the scroll wheel's axle and has 3 contacts below, whereas with an 
IR transmitter, the input probably comes from some type of sensors that the ball feeds. 

• If you have a rotary encoder, well done and carry on. If you have an IR transmitter (as is 
the case with cheapo mice) then it's no good for this. Try a different mouse. 

• Pull out the mouse's scroll wheel from the hole that it sits in and throw it away. 

© Make Projects 

Page 3 of 8 

PowerFake Knob Controller 

Step 2 — Remove and rewire the encoder. 

• Flip over the board and find the 
holes where the rotary encoder is 
soldered in (there should be 3 in a 
row). Note which way the encoder 
points, or you'll solder it backward 
and it won't work properly. 

• Heat the solder points with your 
iron and use either solder wick or a 
desoldering pump to pull off the 
solder from the board, releasing the 

Step 3 

• Solder wires into the 3 encoder pin 
holes on the circuit board. These 
will need to be about 3"-6" long 
depending on your project box size. 

• You can either solder the other 
ends of the wires directly onto the 
corresponding pins of the encoder, 
or you can use a piece of 
stripboard to connect the pins to 
the wires, as I did; this is a bit 
more durable. 

• To get the encoder to fit neatly 
along the edge of my stripboard so 
that the new axle could face 
upward, I bent apart the 2 metal 
tabs that secured each end of the 
package to the original board. 

© Make Projects 

Page 4 of 8 

PowerFake Knob Controller 

Step 4 — Glue the rod in. 

• Find a metal rod that fits through 
the center of your encoder, such as 
a thin nail or a large paperclip. 

• Cut your rod to about 3". It needs 
to be long enough to fit through the 
encoder, through one side of the 
project box, and a good way into 
the car wheel. 

• Put a small dab of super glue onto 
the rod and slide it into the rotary 
encoder's center hole. 

Step 5 — Mount the encoder. 

• Drill a hole in your project box 
that's the same diameter as your 
metal rod, and stick your rod 
through it. 

• Now mount your encoder to the 
inside of your project box. I stuck it 
down with double-sided tape, then 
went over it with regular tape. 

© Make Projects 

Page 5 of 8 

PowerFake Knob Controller 

Step 6 — Mount the wheel and the board. 

• Time to rip the wheel from your 
R/C car. If it comes with a gear in 
it, as mine did, try leaving it in to 
act as a spacer for your wheel. I 
simply used super glue to mount 
my wheel. 

• If your wheel's hole is wider than 
the rod, roll up some paper to pad 
out the hole, or gum it up with Blu- 
Tack poster putty. 

• Tape the circuit board to the bottom 
of the project box and drill a hole in 
the side of the case for the cable to 
escape through. Then clip and/or 
screw the 2 halves of the box 
together and test it! 

© Make Projects 

Page 6 of 8 

PowerFake Knob Controller 

Step 7 — Test it. 

• Plug your new scroll wheel into 
your computer and give it a whirl. I 
use a USB mouse with my PC, so 
the PS/2 port was free. If you used 
a PS/2 mouse like I did, you'll have 
to reboot your PC after plugging it 
in for the BIOS to recognize it. 

• Fire up something scrollable, be it 
your Winamp library, your browser, 
or a massive e-book, and give it a 
test. If you find it's too sensitive or 
not sensitive enough, then go into 
your Control Panel and adjust your 
mouse properties, specifically, how 
many lines you scroll with 1 turn of 
the wheel. 

• As an added bonus, see if your 
wheel has enough momentum to 
scroll under its own weight with a 
flick of the wrist, like mine does. 

Step 8 — Take it a step further. 

• I wanted to emulate the PowerMate as much as possible. A little Googling turned up an 
awesome piece of software called Volumouse . It lets you adjust your PC's volume by 
holding a keyboard button and scrolling up or down. It will also resize windows and change 
brightness, all according to the conditions you give it. 

• See a video of the PowerFake controlling Volumouse at . 

• (This project was originally published on Instructables .) 

© Make Projects 

Page 7 of 8 

PowerFake Knob Controller 

This project first appeared in MAKE Volume 17 . 

Related Posts on Make: Online: 

Weekend Project: The PowerFake .. 
Guitar Game Controller Mods 

This document was last generated on 201 2-1 1 -03 03:55:57 AM. 

© Make Projects Page 8 of 8